Sweat-glands
To revert to the figure (70) at page 165, the little masses at g, g, are grains of fat lying in the meshes of the deeper strata of the skin, or in the structure just below it. And the little balls of twisted tube (f, f) are Glands that secrete the Perspiration; for, the perspiration does not ooze up from the whole surface of the skin, but has a regular system of factories for its formation. A fine tube (h) is seen passing from each of these “sweat-glands,” as they are called. It curls in a spiral manner, like a cork-screw, where it traverses the cuticle to open at the surface. On the palmar aspect of the hand most of these tubes or ducts open along the tops of the fine ridges which are there seen; and with a magnifying glass of moderate power you can distinguish their orifices on the flattened tops of the ridges on your own fingers. These are the “pores of the skin,” respecting which we hear so much, and through which the Roman Bath brings such streams from the subjacent glands.
The sweat-glands are scattered all over the body, but are especially numerous in the palm and in the sole; and the moisture issuing from them tends to keep the skin of these parts soft and moist, and so fitted for the reception of tactile impressions. The quantity of fluid furnished by them varies a good deal in different persons, and under different circumstances. In some persons it is habitually slight; and the hands feel dry and harsh. Or, what is equally disagreeable, it is superabundant; and the hands are habitually damp, perhaps, cold and clammy, staining the gloves and soiling everything they touch. In fever the perspiration is defective; and the dryness and heat of the palm are often the first symptoms of an accession of fever that attract the patient’s notice.
We all know that perspiration is usually increased by exercise, or by the application of warmth to the surface, as by the hot air in the sudatorium of the Roman Bath; and then, by its evaporation, it cools and relieves the body, and contributes to our comfort. We know, too, that it is liable to be increased by any thing that produces a depressing effect, and that it then induces an uncomfortable sensation, chilling the surface too much, and making it cold and clammy. Most of you have experienced the discomfort of the cold sweat caused by fright; and some of you may have felt the cold, clammy hand of one who was suffering under the shock of a severe accident or the prostration caused by the sudden onset of a dangerous malady. Why perspiration should occur under these very different conditions, producing, at one time, so much relief, and, at another, so much additional discomfort, it is not easy to say.